Marker-Assisted Recurrent Selection for Pyramiding Leaf Rust and Coffee Berry Disease Resistance Alleles in Coffea arabica L.

In this study, marker-assisted recurrent selection was evaluated for pyramiding resistance gene alleles against coffee leaf rust (CLR) and coffee berry diseases (CBD) in Coffea arabica. A total of 144 genotypes corresponding to 12 hybrid populations from crosses between eight parent plants with desired morphological and agronomic traits were evaluated. Molecular data were used for cross-certification, diversity study and resistance allele marker-assisted selection (MAS) against the causal agent of coffee leaf rust (Hemileia vastatrix) and coffee berry disease (Colletotrichum kahawae). In addition, nine morphological and agronomic traits were evaluated to determine the components of variance, select superior hybrids, and estimate genetic gain. From the genotypes evaluated, 134 were confirmed as hybrids. The genetic diversity between and within populations was 75.5% and 24.5%, respectively, and the cluster analysis revealed three primary groups. Pyramiding of CLR and CBD resistance genes was conducted in 11 genotypes using MAS. A selection intensity of 30% resulted in a gain of over 50% compared to the original population. Selected hybrids with increased gain also showed greater genetic divergence in addition to the pyramided resistance alleles. The strategies used were, therefore, efficient to select superior coffee hybrids for recurrent selection programs and could be used as a source of resistance in various crosses.

Selection of arabica coffee progenies tolerant to heat stress / Seleção de progênies de café arábica tolerantes ao calor

Due to high temperatures, practically all coffee farms in the state of Rondonia are of the C. canephora species. Thus, importing arabica coffee from other states becomes necessary for composition of blends, as well as for the specialty or gourmet coffee market. The purpose of this study was to select arabica coffee genotypes that exhibit satisfactory agronomic performance under high temperature conditions. The experiment was conducted in OuroPreto do Oeste, RO, Brazil, with mean annual temperature of 25.8°C and mean annual rainfall of 2300mm year-1. The experiment was composed of 114 arabica coffee genotypes, with 103 progenies and eleven control cultivars, provided by EPAMIG. A randomized block experimental design was used with three replications, spacing of 3.0x1.0 meters and five plants per plot. All the crop seasons showed significant difference for the green coffee yield trait. In joint analysis, significant differences were detected among progenies and control cultivars. In the average of the four harvests, green coffee yield was 32.38 bags ha-1. The cultivars 'CatuaíVermelho IAC 15', 'Obatã IAC 1669-20' and 'Catucaí Amarelo 2SLCAK' stood out, achieving yields greater than 40 bags ha-1. The gain obtained from selection was 14.33 bags ha-1, which is equivalent to an increase of 44.04% in production of green coffee. The progeny H514-7-10-6-2-3-9 stood out with an average yield of 51.20 bags ha-1. In regard to maturation cycle, 56% of the progenies were classified as early maturity and 44% as medium maturity. Late maturity genotypes were not observed.

Devido às temperaturas elevadas, basicamente, todas as lavouras de café no estado de Rondônia são da espécie C. canephora. Desse modo, a importação de café arábica de outros estados faz-se necessária para a composição dos blends, além do mercado de cafés especiais ou gourmets. O objetivo deste trabalho foi selecionar genótipos de café arábica que apresentam desempenho agronômico satisfatório sob condições de temperaturas elevadas. O experimento foi instalado em Ouro Preto do Oeste-RO, com temperaturas médias anuais de 25,8°C e precipitação pluvial média de 2.300mm ano-1. O experimento foi composto por 114 genótipos de café arábica, sendo 103 progênies e onze cultivares testemunhas, fornecidas pela EPAMIG. O delineamento foi blocos casualizados com três repetições, espaçamento de 3,0 x 1,0 metros, com cinco plantas por parcela. Todas as safras demonstraram diferença significativa para a característica produtividade de café beneficiado. Na análise conjunta, foram detectadas diferenças significativas entre progênies e entre cultivares testemunhas. Na média das quatro colheitas, a produtividade de café beneficiado foi de 32,38 sacas ha-1. Destaques para as cultivares 'Catuaí Vermelho IAC 15', 'Obatã IAC 1669-20' e 'Catucaí Amarelo 2SLCAK' que alcançaram produtividades acima de 40 sacas ha-1. O ganho de seleção obtido foi de 14,33 sacas ha-1, que equivale a um aumento de 44,04% na produção de café beneficiado. Destaque para a progênie H514-7-10-6-2-3-9, com produtividade média de 51,20 sacas ha-1. Quanto ao ciclo de maturação, 56% das progênies foram classificadas como ciclo precoce e 44% de ciclo intermediário. Não foi observado genótipo de ciclo tardio.